Mobile electronic devices, such as wireless telephones, include user interfaces that have both input and output apparatuses. Input apparatuses permit a user to input information, such as data or commands, to the electronic device and may include keypads, or voice input devices, for example. Output apparatuses allow a mobile device to provide the user with information by displaying information on a display, such as a liquid crystal display, for example, by announcing information using the device's speaker, or by flashing a light emitting diode (LED).
The power available to a mobile electronic device is always limited, and sometimes critically so. In order to “preserve charge,” many schemes have been employed, to greater or lesser success. Some of those schemes attempt to limit the power consumption of mobile devices during periods of relative inactivity. For example, many mobile devices allow a user to manually lock the device's keypad when the device is not going to be in use, so that power is not expended on backlighting a display, inadvertent key presses are not misinterpreted as a desired dialing sequence, or applications are not unintentionally launched. By locking the keypad we mean, simply, that input from the keypad is ignored. Unfortunately, manual locking is somewhat inconvenient and easily overlooked. As a result, precious battery power is often needlessly and uselessly dissipated, inadvertent key presses are misinterpreted as dialing sequences, and application software programs are unintentionally launched.
To overcome the inconvenience of manually locking a device, some electronic devices employ an auto-locking scheme whereby the device is automatically locked after a predetermined period of inactivity. Unfortunately, this approach introduces its own inconvenience because inadvertent key presses, caused by jostling the device within a backpack for example, prevent locking and may also unintentionally launch applications or functions. A convenient way to disable a user interface and thereby prevent unnecessary power consumption or the recognition of inadvertent key presses would be particularly useful.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.